Electrical switches for use in starter motors for i.c. engines

ABSTRACT

An electrical switch is for use in an internal combustion engine starting mechanism of the kind including a starter motor, a pinion driven by the starter motor and engageable with a toothed wheel on the engine, and a solenoid for moving the pinion into engagement with the toothed wheel, the solenoid including an armature having an inner part for moving the pinion and an outer part coupled to the inner part. A switch of this kind includes a housing and first, second and third fixed contacts secured in the housing in spaced relationship and lying in a common plane. A movable carrier is mounted for movement in a direction at right angles to the plane of the fixed contacts and a conductive bridging piece is resiliently mounted on the carrier and is urged to lie in a plane parallel with the plane of the fixed contacts. A sleeve slidably mounted in the housing is engaged at one end with the carrier and projects at its other end from the housing for engagement with the outer part of the armature. A push rod is slidable within the sleeve and projects at one end from the sleeve for engagement by the inner part of the armature, resilient means urging the sleeve and the push rod outwardly. A movable latch member is movable by the push rod and is resiliently urged to a position wherein it projects above the plane of the fixed contacts to prevent the bridging piece engaging the third fixed contact during movement of the carrier towards the fixed contacts. The arrangement is such that in use upon energization of the solenoid the outer part of the armature moves the carrier through the sleeve towards the fixed contacts, the bridging piece engaging the latch member and thus being tilted relative to the carrier during further movement of the carrier. The bridging piece in its tilted condition engages the first and second fixed contacts to complete a first circuit of the starter motor and the latch member is then moved by the push rod when the pinion of the starter motor is fully engaged with the toothed wheel of the engine to permit the bridging piece to return to its original position with respect to the carrier so as to engage the third fixed contact to complete a second circuit of the starter motor. The second circuit when completed causes energization of the starter motor at a full torque value while completion of the first circuit causes energization of the starter motor at a reduced torque value.

United States Patent Ronald Wilson 13 Chelmsley Lane. Marston Green,Birmingham, England [72) inventor [2l Appl. No. 28,317 [22] Filed Apr.14, 1970 [45] Patented Aug. 3, 1971 [32] Priority May 27,1969

[33] Great Britain [3|] 26636/69 [54] ELECTRICAL SWITCHES FOR USE INSTARTER Primary Examiner-G. R. Simmons Attorney-Holman, Glascock,Downing & Seebold ABSTRACT: An electrical switch is for use in aninternal combustion engine starting mechanism of the kind including astarter motor, a pinion driven by the starter motor and engageable witha toothed wheel on the engine, and a solenoid for moving the pinion intoengagement with the toothed wheel, the solenoid including an armaturehaving an inner part for moving the pinion and an outer part coupled tothe inner part. A switch of this kind includes a housing and first,second and third fixed contacts secured in the housing in spacedrelationship and lying in a common plane. A movable carrier is mountedfor movement in a direction at right angles to the plane of the fixedcontacts and a conductive bridging piece is resiliently mounted on thecarrier and is urged to lie in a plane parallel with the plane of thefixed contacts. A sleeve slidably mounted in the housing is engaged atone end with the carrier and projects at its other end from the housingfor engagement with the outer part of the armature. A push rod isslidable within the sleeve and projects at one end from the sleeve forengagement by the inner part of the armature, resilient means urging thesleeve and the push rod outwardly. A movable latch member is movable bythe push rod and is resiliently urged to a position wherein it projectsabove the plane of the fixed contacts to prevent the bridging pieceengaging the third fixed contact during movement of the carrier towardsthe fixed contacts. The arrangement is such that in use uponenergization of the solenoid the outer part of the armature moves thecarrier through the sleeve towards the fixed contacts, the bridgingpiece engaging the latch member and thus being tilted relative to thecarrier during further movement of the carrier. The bridging piece inits tilted condition engages the first and second fixed contacts tocomplete a first circuit of the starter motor and the latch member isthen moved by the push rod when the pinion of the starter motor is fullyengaged with the toothed wheel of the engine to permit the bridgingpiece to return to its original position with respect to the carrier soas to engage the third fixed contact to complete a second circuit of thestarter motor. The second circuit when completed causes energization ofthe starter motor at a full torque value while completion of the firstcircuit causes energization of the starter motor at a reduced torquevalue.

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INVENTOR 614/42 I ORNEYS ELECTRICAL SWITCHES FOR USE IN STARTER MOTORSlFOR LC. ENGINES This invention relates to electrical switches for usein internal combustion engine starting mechanism of the kind including astarter motor, a pinion driven by the starter motor and engageable witha toothed wheel on the engine, and a solenoid for moving the pinion intoengagement with said toothed wheel, said solenoid including an armaturecomprising an inner part movable axially to move the pinion, and anouter part surrounding said inner part and movable axially in responseto energization of the solenoid, said outer part being coupled to saidinner part through a spring so that said inner part normally moves withsaid outer part and said spring permitting said outer part to moverelative to the inner part when the inner part is held against movementby tooth'to tooth engagement of the pinion and said toothed wheel.

According to the invention, an electrical switch for use in a startingmechanism of the kind specified includes, a housing, first, second andthird fixed contacts secured in the housing in spaced relationship andlying in a common plane, a movable carrier mounted for movement in adirection at right angles to the plane of said fixed contacts, aconductive bridging piece resiliently mounted on said carrier and urgedto lie in a plane parallel with the plane of said fixed contacts, asleeve slidably mounted in the housing and engaged at one end with saidcarrier and projecting at its other end from the housing for engagementby said outer part of said armature, a push rod slidable within saidsleeve and projecting at one end from the sleeve for engagement by saidinner part of said armature, resilient means urging said sleeve and saidpush rod outwardly, and a movable latch member resiliently urged to aposition wherein it projects above the plane of the fixed contacts andprevents said bridging piece engaging said third fixed contact duringmovement of said carrier towards said fixed contacts, said latch memberbeing movable by said push rod, and the arrangement being such that inuse upon energization of the solenoid said outer part of the armaturemoves said carrier through said sleeve towards the fixed contacts, saidbridging piece engaging said latch member and thus being tilted relativeto the carrier during further movement of the carrier, the bridgingpiece in its tilted condition then engaging the first and second fixedcontacts to complete a first circuit of the starter motor and said latchmember being moved bysaid push rod when said pinion of the startermotoris fully engaged with the toothed wheel of the engine to permitsaid bridging piece to return to its original position with respect tothe carrier so as to engage the third fixed contact to complete a secondcircuit of the starter motor, said second circuit when completed causingenergization of the starter motor at a full torque value whilecompletion of said first circuit causes energization of the startermotor at a reduced torque value.

In the accompanying drawings,

FIG. 1 is a sectional view of an electrical switch according to oneexample of the invention,

FIG. 2 is a sectional view on the line 2-2 in FIG. 1, and

FIG. 3 is a diagrammatic view of a starting mechanism for an internalcombustion engine.

Referring to the drawings, the switch includes a synthetic resin moldedhousing 11 which is adapted to be secured to the casing 12 of a startermotor solenoid 10. Adjacent its ends remote from the casing 12, thehousing 11 carries three angularly spaced fixed contacts 13, 14, 15, thecontact surfaces of the contacts 13, M, 15 lying in a common planegenerally at right angles to the axis ofthe casing 12, and each ofthefixed contacts including a portion which extends through the wall of thehousing 11 and defines an external terminal. The housing 11 is closed bya mild steel plate which constitutes a partition wall 16 between thehousing 11 and the casing 12, the partition wall carrying a hollow polepiece 17 which extends axially into the casing 12. Slidably mounted inthe pole piece 17 and extending into the casing 12 at one end, andextending into the housing 11 at its other end is a metal sleeve 18which is urged towards the casing 12 by a compression spring 19 actingbetween the housing 11 and an integral shoulder formed in the bore ofthe sleeve 18. Within the housing 11 the sleeve 18 is formed with anexternal shoulder 21 and carried by the sleeve 11 in abutting engagementwith the shoulder 21 is a molded, insulating carrier 22, the carrier 22being secured to the sleeve 18 by deforming the end of the sleeve 18outwardly. An insulating washer 23 is trapped between thedeformedportion of the sleeve 18 and the carrier 22, and loosely mounted on thecarrier 22 is a copper bridging piece 24. The washer 23 lies generallyat right angles to the sleeve 18, and the bridging piece 24 is urgedagainst the washer 23 by three angularly spaced springs 25 actingbetween the bridging piece 24 and the carrier 22. Thus, the bridgingpiece 24 is urged by the springs 25 to lie generally parallel with theplane of the fixed contacts l3, 14, 15.

Slidably mounted within the sleeve 18 and projecting at its ends fromthe sleeve 18 is a metal push rod 26, the rod 26 being urged towards thecasing 12 by a spring 27 acting between the end of the spring 19 and ashoulder 26:: on the rod 26, the sleeve 18 being formed with an internalshoulder against which the shoulder 26a of the rod 26 abuts. The spring27 surrounds the rod 26, and the bore through the sleeve 18 is formedwith clearance to accommodate the spring 27, and moreover, the spring 27is of a much lower rate than the spring 19. At its-end remote from thecasing 12 the housing 11 is formed with a recess 28 which is partiallyclosed by an internal shoulder 29 against which one end of the spring 19abuts. Positioned within the recess 28 on the side of the shoulder 29remote from the casing 12 is one limb 32 of a crank lever 31. The otherlimb 33 of the lever 31 extends towards the bridging piece 24, and thelever is pivotally mounted, intermediate its ends, on the wall of thehousing 11. A hairpin spring acts between the lever 31 and the housing11, and urges the lever 31 to pivot to a position wherein the limb 33 ofthe lever extends generally parallelwith the sleeve 18, and the limb 32thereof extends generally at right angles to the sleeve 18, the limb 32engaging the shoulder 29 to prevent further movement of the lever underthe action of the hairpin spring. The limb 33 of the lever 31 is sodimensioned that in the rest position of the lever 31, the free end ofthe limb 33 is closer to the bridging piece 24than are the fixedcontacts 13, 14, 15.

In use, the armature of the solenoid 10 is slidably mounted within thecasing 12, the armature including an outer sleeve 34 which is attractedtowards the pole 17 when the solenoid is energized, and an inner shaft35 which is coupled, at one end, to the outer sleevethrough, springs 36,and coupled at its other end through a lever arrangement 37 to thepinion 38 of a starter motor 39. The arrangement is such that when thesolenoid 10 is energized the armature thereof is drawn towards the polepiece 17 thereby moving the pinion 38 of the starter motor 39 towards atoothed wheel 41 on the engine with which the starter motor isassociated. Assuming that the pinion 38 moves into full engagement withthe toothed wheel 41 without any obstruction, then the shaft 35 and thesleeve 34 of the armature will move as one. However, should the pinion38 abut against the'toothed wheel 41 in tooth to tooth engagement, thenthe shaft 35 will be arrested after moving a short distance, and thesleeve 34 will continue to move, the springs 36 coupling the shaft 35and the sleeve 34 being compressed.

The fixed contact 13 of the switch is, in use, electrically connected tooneterminal of a DC source, the other terminal ofthe DC source beingearthed. The fixed terminal 14 is electrically connected through one ofthe'four field windings of the starter motor 39 to earth, and the fixedcontact 15 is elec trically connected through the other three fieldwindings of. the starter motor 39to earth.

The operation of the switchis as follows. When the solenoid 10 isenergized, the armature of the solenoid starts to move towardsthe polepiece IV'ag'ainst the action of an armature return spring (notshown )andthe shaft 35 of the armature engages the rod 26 and moves the rod 26relative to the sleeve 18 until the sleeve 34 of the armature engagesthe sleeve 18 whereafter the sleeve 18 and the rod 26 are movedtogether, the pinion 38 of the starter motor 39 being moved towards thetoothed wheel 41 of the engine. During this movement, the carrier 22together with the bridging piece 24 are being moved towards the fixedcontacts 14, 15, 16. The dimensions of the parts of the switch and thearmature are such that when the armature has completed its full stroke,the bridging piece 24 will be in engagement with the contacts 13, 14,15.

Assuming that the pinion 38 engages the toothed wheel 41 in tooth totooth engagement, then the pinion 38 and the shaft 35 of the armaturewill be arrested, and so the rod 26 will cease to be moved by the shaft35. However, the sleeve 34 of the armature will continue to move,thereby stressing the springs 36 and the sleeve 18 and the carrier 22will continue to move with the sleeve 34 of the armature, and will moverelative to the rod 26 until the internal shoulder of the sleeve 18engages the shoulder 26a of the rod. The rod 26 will then be moved withthe sleeve 18 since the shoulder 26a of the rod 26 is abutting againstthe internal shoulder of the sleeve 18. The limb 33 of the lever 31 isat this time adjacent the contact 15, and closer to the bridging piece24 than the contact and so the movement of the sleeve 18 will move thebridging contact 24 into engagement with the limb 33 of the lever 31.Further movement of the sleeve 18 will cause the bridging piece 24 totilt relative to the carrier 22 compressing some of the springs sincethe bridging piece 24 is engaged with the limb 33, and so that bridgingpiece 24 will only engage the contacts 13, 14. The bridging piece 24completes the circuit between the contacts 13, 14 thereby energizingsaid one field winding of the starter motor 39 and operating the motorin a low torque condition. Thus the pinion 38 of the starter motor willbe rotated relative to the toothed wheel 41, and the tooth to toothengagement of the pinion 38 and the toothed wheel 41 will be broken. Thepinion will then be moved into full engagement with the toothed wheel 41under the action of the springs 36, and'the shaft 35 of the armaturewill be moved towards the rod 26. The length of the rod is such that itwill be engaged by the shaft 35 before the shaft 35 has completed itsfull movement under the action of the springs 36 and so the rod 26 willbe moved by the shaft 35 relative to the sleeve 18, towards the end ofthe housing 11 remote from the casing 12. The bridging piece 24 isformed with a slot adjacent the point at which the limb 33 of the lever31 engages the bridging piece 24, and the rod 26 is so dimensioned thatas the pinion 38 achieves full engagement with the toothed wheel 41 thenthe rod 26 strikes the limb 32 of the lever 31, thereby pivoting thelever 31 relative to the housing and moving the limb 33 of the lever 31into the slot in the bridging piece 24. When the lever 31 is pivoted,the bridging piece 24 is no longer spaced from the contact 15 by thelimb 33, and so is moved by the springs 25 into engagement with thecontact 15 in addition to the contacts l3, 14. Thus when the pinion 38is in full engagement with the toothed wheel 41, the bridging piece 24is permitted to complete also the circuit through the remaining threefield windings of the starter motor 39 so that the starter motor isoperated at high torque and cranks the engine to start the engine.

When the solenoid 10 is deenergized, the armature return spring movesthe armature away from the pole piece 17, and the springs 19, 27 returnthe sleeve 18 and the rod 26, together with the carrier 22 and thebridging piece 24, to their original positions, thereby breaking thecircuits through the windings of the starter motor 39. It will beappreciated, that since the contacts 13, 14, l5'lie in the sameplane,then both circuits of the motor will be broken simultaneously. in therest position of the carrier 22 the bridging piece 24 is spaced from thelimb 33 of the lever 31, and so the lever 31 returns to its originalposition in readiness for a further operation.

Upon energization of the solenoid 10 should the pinion 38 of the startermotor have moved immediately into full engagement with the toothed wheel41 of the engine, then the shaft and sleeve of the armature would havemoved as one, thereby moving the sleeve 18 and the push rod 26 to causethe closure of the contacts 13, 15, fractionally after the closure ofthe contacts 13, 14.

In the preferred embodiment the lever 31 is formed from insulatingmaterial, but it is envisaged that if desired the end of the rod 26which engages the lever 31 could carry an insulating cap so that thelever 31 need not be formed from insulating material.

lCLAlM:

1. An electrical switch for use in a starting mechanism of the kindspecified including a housing, first, second and third fixed contactssecured in the housing in spaced relationship and lying in a commonplane, a movable carrier mounted for movement in a direction at rightangles to the plane of said fixed contacts, a conductive bridging pieceresiliently mounted on said carrier and urged to lie in a plane parallelwith the plane of said fixed contacts, a sleeve slidably mounted in thehousing and engaged at one end with said carrier and projecting at itsother end from the housing for engagement by said outer part of saidarmature, a push rod slidable within said sleeve and projecting at oneend from the sleeve for engagement by said inner part of said armature,resilient means urging said sleeve and said push rod outwardly, and amovable latch member resiliently urged to a position wherein it projectsabove the plane of the fixed contacts and prevents said bridging pieceengaging said third fixed contact during movement of said carriertowards said fixed contacts, said latch member being movable by saidpush rod, and the arrangement being such that in use upon energizationof the solenoid said outer part of the armature moves said carrierthrough said sleeve towards the fixed contacts, said bridging pieceengaging said latch member and thus being tilted relative to the carrierduring further movement of the carrier, the bridging piece in its tiltedcondition then engaging the first and second fixed contacts to completea first circuit of the starter motor and said latch member being movedby said push rod when said pinion of the starter motor is fully engagedwith the toothed wheel of the engine to permit said bridging piece toreturn to its original position with respect to the carrier so as toengage also the third fixed contact to complete a second circuit of thestarter motor, said second circuit when completed causing energizationof the starter motor at a full torque value while completion of saidfirst circuit causes energization of the starter motor at a reducedtorque value.

2. A switch as claimed in claim 1 wherein said latch member is in theform of a cranked lever having first and second limbs, said lever beingresiliently urged to a position wherein said first limb extendsgenerally at right angles to said sleeve and said second limb extendsgenerally parallel to said sleeve and above the plane of the fixedcontacts.

3. A switch as claimed in claim 2 wherein said bridging member is formedwith a slot so that when said lever is pivoted by said push rod saidsecond limb of the lever is moved into said slot to permit said bridgingmember to return to its original position relative to the carrier so asto engage said third fixed contact.

1. An electrical switch for use in a starting mechanism of the kindspecified including a housing, first, second and third fixed contactssecured in the housing in spaced relationship and lying in a commonplane, a movable carrier mounted for movement in a direction at rightangles to the plane of said fixed contacts, a conductive bridging pieceresiliently mounted on said carrier and urged to lie in a plane parallelwith the plane of said fixed contacts, a sleeve slidably mounted in thehousing and engaged at one end with said carrier and projecting at itsother end from the housing for engagement by said outer part of saidarmature, a push rod slidable within said sleeve and projecting at oneend from the sleeve for engagement by said inner part of said armature,resilient means urging said sleeve and said push rod outwardly, and amovable latch member resiliently urged to a position wherein it projectsabove the plane of the fixed contacts and prevents said bridging pieceengaging said third fixed contact during movement of said carriertowards said fixed contacts, said latch member being movable by saidpush rod, and the arrangement being such that in use upon energizationof the solenoid said outer part of the armature moves said carrierthrough said sleeve towards the fixed contacts, said bridging pieceengaging said latch member and thus being tilted relative to the carrierduring further movement of the carrier, the bridging piece in its tiltedcondition then engaging the first and second fixed contacts to completea first circuit of the starter motor and said latch member being movedby said push rod when said pinion of the starter motor is fully engagedwith the toothed wheel of the engine to permit said bridging piece toreturn to its original position with respect to the carrier so as toengage also the third fixed contact to complete a second circuit of thestarter motor, said second circuit when completed causing energizationof the starter motor at a full torque value while completion of saidfirst circuit causes energization of the starter motor at a reducedtorque value.
 2. A switch as claimed in claim 1 wherein said latchmember is in the form of a cranked lever having first and second limbs,said lever being resiliently urged to a position wherein said first limbextends generally at right angles to said sleeve and said second limbextends generally parallel to said sleeve and above the plane of thefixed contacts.
 3. A switch as claimed in claim 2 wherein said bridgingmember is formed with a slot so that when said lever is pivoted by saidpush rod said second limb of the lever is moved into said slot to permitsaid bridging member to return to its original position relative to thecarrier so as to engage said third fixed contact.